Air conditioning system utilizing refrigeration



M arch 28, 1939. s. M ANDERSON AIR CONDITIONING SYSTEM UTILIZING REFRIGERATION Filed March 15, 1936 '2 Sheets-Sheet 1 17706212702" SA UEL, 'M ,qupsedmv JCQAMZ attorney s. M ANDERSON March 28, 1 93 9.

. AIR CONDlTIONING SYSTEM UTILIZING REFRIGERATION iled March 13, 1956 2 Sheets-Sheet 2 Dzverribr S UEL M. 44/051260,

2,? w J 9 afibr'wg u Patented Mar. 28, 1939 UNITED, STATES AIR CONDITIONING SYSTEM UTILIZING REFRIGERATION I Samuel M. Anderson, Sharon, Mass., assignor to B. F. Sturtevant Company, Inc., Boston, Mass.

Application March 13, 1936, Serial No. 68,698

3 Claims. (Cl. 62-6) This invention relates to air conditioning systems utilizing refrigeration and relates more particularly to an air conditioning system for passenger vehicles, combining evaporative cooling with cooling by refrigeration.

The passenger cars on some railroad lines on one continuous trip, pass through regions in which, in summer, difierent demands are made upon the air conditioning equipment. For example, a train may first pass through a region having a high wet bulb as well as a high dry bulb temperature, requiring considerable 'refrig-' erating energy for the cooling and dehumidification of the air. The train may next pass through a region having such a low wet bulb temperature that evaporative cooling may be effectively employed. Then at night, a suflicient cooling eflect may be secured by forcing an increased volume of outside air through the car.

According to this invention, a spray cooling system is supplied with refrigeration when conditions require such; is operated in evaporative cooling when efiective, and when effective; the

' sprays are discontinued and the cooling effect is secured by the circulation of an increased volume of outside air. Indicators are provided for indicating changes in conditions enabling changes in the operation of the conditioner, and controls are provided for changing the method of operation of the conditioner. and for maintaining the desired indoor conditions, with a minimum of equipment and without operating difliculties.

An object of the invention is to provide means and methods for efiective air conditioning with and without refrigeration.

Another object of the invention is to provide a switching arrangement with'indicators and controls for the effective conditioning of air utilizing refrigeration when needed and dispensing with refrigeration when not needed.

Other objects of the invention will be apparent from the following description taken together with the drawings. I

The invention will now be described with reference to the drawings of which:

Fig. 1 is a diagrammatic view of the invention as applied to a railroad passenger car;

Fig. 2 is a side sectional view of a railroad passenger car equipped according to this invention;

Fig. 3 is a plan view in section of the car of Fig. 2; and

Fig. 4 is a cross-sectional view of the car.

The system illustrated was designed for a particular railroad line extending across a particular section of North America. The design was based upon the knowledge that during one period of travel the maximum outdoor temperatures to be expected were 95 dry bulb and 72 wet bulb. With such temperatures, it was de- 5 termined that a sleeping car with 50 passengers could be maintained comfortable at a 77 dry bulb temperature and 62% relative humidity by the circulation of 2220 cubic feet per minute of 40% outdoor air and 60% recirculated air cooled by passage through water sprays chilled by an ice meltage at a rate of 5 tons per 24 hours, in an ice chamber.

During another period of travel the outdoor dry bulb temperature remains at 95 but the outdoor wet bulb temperature decreases to 61. This permits evaporative cooling; the sprayrwater is by-passed around the ice chamber, and all outside air passes through the conditioner. The spray conditioner is so designed that the recirculated spray water is chilled by evaporative cooling to 61 and the air leaving the conditioner will be cooled to about 62. The discharge of this air into the car maintains the desired standard of 77and 62% relative humidity. I

During another period of travel the outdoor temperature at times as at night, drops to 72.8 dry bulb with 68.1 wet bulb. At such time, the sprays are discontinued and the fan system is converted to force 4,000 cubic feet per minute of outside air through the car. This maintains the car at 76 dry bulb and even though the relative humidity may rise as high as 76% inside the car, the eifective temperature which is a measure of human comfort, is unchanged, and the air is comfortable.

A control panel is provided with four positions marked as High, "Medium, Medium low, and Low. When the controls are switched by a train attendant to High", a temperature of 76 dry bulb is maintained in the car by the passage of 4,000 cubic feet of outside air, without temperature conditioning, through the car. A red light on the panel lights when the outdoor dry bulb temperature drops below 73 which is low enough for this cooling by ventilation to be sufwith outdoor dry bulb above 73, a blue light will appear in the panel with the red light out. This ,is a signal to the train attendant that cooling.

by refrigeration is required and he switches the controls to accomplish this and to pass recirculated air through the conditioner. A car thermostat regulates the spray water.

With the blue light still on the panel, another adjustment is provided for satisfying possible passenger complaints that the air is too cold. The porter then switches the controls to decrease the volume of air passing through the conditioner, to 1350 cubic feet per minute.

As the outdoor temperature decreases, the train attendant is warned, of course, by the lights on the panel to switch the controls towards the High position. When, however, the outdoor temperature has dropped to a point where with the controls at High, the passenger space is too cold, the train attendant shuts down the cooling a paratus and operates the ordinary heat control (not shown) to supply heat to the car.

The operation of the conditioner and of the controls will now be described with reference to Fig. 1 of the drawings.

The conditioner 6 located in the upper portion of the right hand end (facing the drawing) of the car is provided with the spray nozzles 1, the fans 8, the outside air inlet In, the recirculated air inlet II, and the air discharge outlet |2. The fans 8 are driven'by the motor |3 energized by the battery l4. A filter is provided in the inlet |0. The ice chamber l5 supplies ice water to the spray nozzles 1, through the intermediary of the pipe I6; pump H and pipe l8. The water collected from the sprays in the conditioner 6 is returned through the pipe l9, to the ice chamber |5 for recooling. v

' At the opposite end of the car from the conditioner 6 is arranged the blowers 28, driven by the motor 2| which is connected in parallel to the motor l3 for the conditioner 6. The blowers 29 handle all outside air drawn in through the inlet 22 which like the outside air inlet I is provided with a filter. The outside air leaving the blowers 20 passes through the outlet 23 into the passenger space.

When the outdoor wet bulb temperature is above 61 F., the wet bulb thermostat 24 mounted in the outside air passage 25, closes a circuit including the wire 26, battery l4, the wire 21, the contacts 28, the arm 29, the filaments of the blue lights 30 and 3|, the wire 32 and the wire 33. This causes the lights 36 and 3| to glow, indicating to the train attendant that the switch arm 34 should be moved to a position in line with the light 3|. When this is done, the resistor contact 35 moves against the point 31 on the resistor 36, in circuit with the blower driving motors l3 and 2|, placing sufiicient of the resistor 36 in the circuit of those motors to enable them to operate at a speed to provide 2220 cubic feet of air per minute. The energizing circuits of the motors l3 and 3| include the battery l4, the wire 38, the switch arm 34, the contact 35, the resistor 36 at point 31, the switch 39, the wires 46 and4| and the motor buses 42 to the motors l3 and 2|.

The switch arm 34 provides for the supply of refrigeration by closi g a circuit including the motor '43driving the pump 1, the wire 44, the

battery l4, the wire 38, the arm 34, the segment in the ice chamber 46, and the wire 41. The pump then operates to supply water to the spray nozzles 1.

In order to ensure that the water supplied at this time to the nozzles 1 is ice water, the switch arm 34 closes a circuit including the solenoid 48, the wire 49, the battery I4, the wire 38, the arm 34, the segment 56 and the wire This energizes the solenoid 48 to adjust the valve 52 to close off the by-pass pipe 53 around the ice chamber l5, and to open the pipe 54 to the spray nozzles in the ice chamber.

The mercury type thermostat 55 acts to maintain the desired dry bulb temperature of 77 in the car by controlling through the control valve 56, the volume of refrigerated water supplied to the sprays in the conditioner 6. When the temperature in the car is at or above 77, a circuit including the thermostat 55, the wire 51, the solenoid 58, the wire 59, the battery l4, and the wire 49 is closed. This energizes the solenoid to hold open the valve 56. When the temperature falls below 77, this circuit is opened, the solenoid 58 is deenergized and the valve 56 is partially closed to decrease the volume of water supplied to the spray nozzles 1.

If the passengers complain that the air is too cold, the train attendant by moving the switch arm 34 in line with the blue light 30, reduces the air volume to 1330 cubic feet per minute, the other apparatus functioning as before. Due to the decreased air volume, the temperature should rise to 78. If the temperature rises above 78, the car thermostat 55 automatically adjusts the valve 60 to provide an increased water volume to the spray nozzle 1. This is accomplished by the thermostat '55 closing a circuit including the wire 6|, the solenoid 62, the wire 63, the contact 64, the switch arm 34, the wire 38, the battery l4 and the wire 49. The solenoid 62 is thus energized to open completely the fomierly partially closed valve 60. When the temperature falls again to 78, this circuit is opened and the valve 60 is partially closed.

When the outdoor wet .bulb temperature drops to 61 F., the wet bulb thermostat 24 opens the above described circuit including the blue lamps 30 and 3|, and the wet bulb thermostat 64 closes a circuit including the wire 65, the relay 45, the battery l4, the wire 21, the contacts 66, the switch 61, the wire 68, the white lamp 69, and the wire 10, The resulting lighting of the white lamp 69 indicates to the train attendant that outdoor conditions are such that cooling by evaporation may sufiice. He then moves the switch arm 34 in position, the above described circuit including the segment 50 and the solenoid 48 is opened, causing the solenoid to become deenergized and to adjust the valve 52 to close ofi the pipe 54 I5 and to open the by-pass pipe 53, this causing the Water returned from the spray nozzles 1 to by-pass the ice chamber I5, so thatcooling is effected by evaporative cooling. The fan speed remains unchanged due to the same value of the resistor remaining in the fan motor circuit. The car thermostat 55 maintains the car temperature at 77 during this period of evaporative cooling by control of the water throttling valve 56 as previously described.

When the outdoor dry bulb temperature drops to 72.8 F., the thermostat I6 closes a circuit including the wire 11, the wire 65, the relay 45, the battery l4, the wire 21, the solenoid 18, the wire 19, the red lamp 8|, and the wire 80. This causes as described in the immediate foregoing, the relay 45 to energize the dampercontrol motor 13 to close the recirculated air dampers. It also causes the thermostat 55 from controlling the blower speed except when the switch arm 34 is at g The solenoid 18 which is energized when the red light is on, opens the circuits of the blue lamps 30 and 3| by moving the arm away from the contacts 28, and the arm 81 away from the contacts 66. This prevents the blue lights from glowing at the time that the red light is on.

The following tabulation illustrates at a glance, the practical operation of the apparatus described in detail in the foregoing:

Outside temperature 72.8 deg. D. B. 95 deg. D. B. 95 deg. D. B. 95 deg. D. B 68.1 deg. W. B. 61 deg. W. B. 72 deg. W. B. 72 deg. W. B Control set High Medium Medium low Low Car temp. maintained in- 76 deg. D. B 77 deg. D. B. 77 deg. D. B. 78 deg. D. B side 70 deg. W. B 68 deg. W. 68 deg. W. B. 65 deg. W. B 73 deg. E. T 73 deg. E. T. 73 deg. E. T 72 deg. E. T 76 R. H. 62% R. H. 62% R. H. 50% R. H.

Car thermostat Regulates air Regulates spray Regulates spray Regulates spray Total all 4,000 c. i in 2,220 e. f. m. 2,220 c. i. m. 1,330 c. i. in.

Outside air 100% 100% 40% 40% Recirculated 0% 60% 60% Fans running 4 4 4 4 Appx. fan. H. I. H. P. }g H. P. 36 H. P. 54 H. P.

Electric pump Oil On On On Gals. per min. 0 G. P. M. 19 G. P. M. 19 G. P. M. 13 G. P. M.

Water temp. 61 deg. F. 40 deg. F. 40 deg. F.

Ice .bin cooling Oil Oil On On Appx. pump H. P. 0 H. P. H. P. M H. P.

Cooling results from Rapid introduction of Evaporation of spray wa- Cold iced spray water in Cold iced spray water in large quantities 0! cool tor into dry outside air contact with recirc. and contact with recirc. and outside air outside air outside air.

Telltale light indicator Red lights when outside White lights when outside Blue lights when outside Blue lights when outside D. B. thermostat indi- W. B. thermostat indi- W. B. thermostat indi- W. B. thermostat indicates a dry bulb temp. cetes a wet bulb temp. cates a wet bulb temp. cates a wet bulb temp. below 73 F. at or below 61 deg. F. above 61 deg. F. above 61 deg. F.

When red light is on neither'white nor blue cam light because of interlocking controls.

Control instructions to 1. Turn to High" when red-light is on.

porter 2. Turn to Mcdiurn" when white light is on.

3." Turn to Med. Low when blue light is on. 4. Turn to Low" when blue light is on only to satisfy passenger complaints.

the red lamp 8l to glow, indicating to the train attendant that suflicient cooling may be supplied by discontinuing the sprays and by increasing the outside air volume. He then moves the switch arm 34 in line with the red lamp 8|, to High position. The arm 34 leaves the segment 46 causing the above described circuit including the pump motor 43 to be broken, thus shutting down the pump l1, and thesupply of water to the sprays. The contact 35 moves with the switch arm 34 to remove all of the resistance 36 from the circuit of the blower driving motors l3 and 2|, causing these motors to rotate at an increased speed to cause the blowers 8 and 20 to force 4,000 cubic feet per minute of outside air through the car.

With the switch arm 34 at High position, the car thermostat 55 controls the car temperature by varying the blower speed from a rate of 4,000 ciibic feet of air per minute to a rate of 3,000 cubic feet of air per minute. When the temperature within the passenger space drops below 76, the thermostat 55 acts to opena shunt across the resistor 85, placing it in'series with the current supply to the blower driving motors to reduce their speed. Normally, the temperature is above 76 with the result that a circuit including the thermostat 55, the solenoid 86 and a battery is closed, causing the solenoid 86 to hold its switch arm 81 against the contact 88, thus maintaining the resistor 85 shunted out of the blower motors energizing circuit. The contacts of the switch 39 are connected across the resistor 85, maintaining the resistor shunted out of service, except when the switch arm 34 is at High position, at which time the extension 89 on the contact arm 35, presses against the extension 98 of the switch 39, causing it to open. This prevents The manually operated control panel could of course be replaced by a completely automatic control, in which case, the thermostats in the outside air passage would act to energize solenoids for closing the contacts on the control panel. The manually operated control panel is preferred because of its ease of adjustment, simplicity, and'for the additional reason that the railroad line for which the system was designed, prefers such an arrangement.

Figs. 2, 3, and 4 illustrate the preferredarrangement of the apparatus together with a. novel duct system. The'blowers 28 discharge into one end of the ducts 9| and the blowers 8 discharge into the other end of the same ducts. This arrangement enables considerably more air to be moved through the passenger space than has been the practice in the past. The ducts 9| discharge into the passenger space through the spaced overhead outlets 92 and into the lower berths through vertical ducts 93 and outlets 94.

While one embodiment of the invention has been described for the purpose of illustration, it should be understood that the invention is not limited to the exact arrangement described, since many departures will suggest themselves to those outside air supplied to said cooler, for effecting cooling by the ventilating efiect of an increased volume of outside air when its temperature is sufficiently low for such to be eifective, a control panel, and controls on said panel for controlling all of said means.

2. Air conditioning control apparatus for a passenger vehicle having an air washing system adapted to operate alternatively in refrigerative cooling or evaporative cooling cycles, comprising a visual signal in said vehicle for indicating when said system should be operated in the evaporative cooling cycle, and means responsive to changes in the wet bulb temperature of outdoor air entering said system for actuating said signal when the wet bulb temperature of the outdoor air has fallen to a predeterminedminimum point.

3. 'Air conditioning control apparatus for a passenger vehicle having an air cooling system, comprising a pair of signal lamps in said vehicle for indicating when adjustments'should be made in said system, means responsive to changes in the wet bulb temperature of the outdoor air entering said system for actuating one of said lamps when the wet'bulb temperature of the outdoor air has fallen to a predetermined point, and means responsive to changes in the dry bulb temperature of the outdoor air entering said system for actuating the other of said lamps when the dry bulb temperature of the outdoor air has fallen to a predetermined point.

SAMUEL M. ANDERSON. 

